Food-Reinforced Response Decrements as a Function of Amount of Ionizing X-Irradiation

Abstract

32 malt albino rats, about 90, 120, or 150 days of age and weighing between 240 and 340 gm. at the start of the experiment, were employed in a study in which whole body X-irradiation dose level was the independent variable and number of VR-3 food reinforced bar-presses pet session the dependent variable. On the 12th day of training, Ss were assigned without bias to one of the four following whole-body X-irradiation doses: (1) 0 rad, (2) 285 rad, (3) 570 rad, or (4) 855 rad. An analysis of responses made by the four treatment groups over 10 days of post-irradiation observation yielded significant main effects attributable to differences in amount of X-irradiation and to daily experimental sessions. The interaction of days with level of irradiation was also significant. The amount of initial response decrement was directly related to the amount of irradiation received, with maximum differentiation occurring about the fourth day after treatment.